#include <stdio.h>
#include <stdlib.h>

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */

// 已经排序过的 list 证明所有相同的数字都是在一起的

struct ListNode {
     int val;
	 struct ListNode *next;
};

struct ListNode* deleteDuplicates(struct ListNode* head) {
    return head;
};

int main() {
    struct ListNode *l1 = (struct ListNode *)calloc(5, sizeof(struct ListNode));
    struct ListNode *p = NULL;
	
    p = l1;
    p->val = 1;
    p->next = l1 + 1;
    p = p->next;

    p->val = 1;
    p->next = l1 + 2;
    p = p->next;

    p->val = 3;
    p->next = l1 + 3;
    p = p->next;

    p->val = 3;
    p->next = l1 + 4;
    p = p->next;

    p->val = 3;
    p->next = NULL;

    p = l1;
    while (p) {
        printf("%d ", p->val);
        p = p->next;
    }
    printf("\n");
	
	return 0;
}